Evacuated hermetically sealed package with semirigid shell and stretchable closure

ABSTRACT

EVACUATED HERMETICALLY SEALED PACKAGE COMPRISING A TOP OF STRECTHABLE PLASTIC FILM SEALED TO A SEMI-RIGID SHELL CONTAINING A PRODUCT WITH THE STRETCHABLE TOP IN TIGHT CONTACT WITH THE UPPER SURFACE OF THE PRODUCT. THE PACKAGE IS FORMED BY APPARATUS INCLUDING A PACKAGING HEAD HAVING PRELIMINARY AND FINAL SEALING MEANS. THE PRELIMINARY SEALING MEANS INCLUDE HEAT SEAL BARS EXTENDING PART WAY AROUND THE PERIPHERY OF THE SHELL AND A HEATING ELEMENT MOUNTED WITHIN THE SPACE INTERIORLY OF THE SEAL BARS WHICH SOFTENS THE TOP AND RENDERS IT READULY STRETCHABLE IN THE AREA INBOARD OF THE SEAL LINE. FINAL SEAL MEANS INCLUDING AN EVACULATING CHAMBER AND MEANS TO COMPLETE THE SEAL BETWEEN THE TOP AND SHELL. THE APPLICATION OF ATMOSPHERIC PRESSURE UPON VENTING THE EVACUATION CHAMBER CAUSES THE TOP TO STRETCH INWARDLY AGAINST THE PRODUCT.

Oct. 3, 1972 w. E. YOUNG ETAL EVACUATED HERMETICALLY SEALED PACKAGE WITHSEMIRIG SHELL AND STRETCHABLE CLOSURE Griginal Filed Sept. 1, 1965 2Sheets-Sheet l mm Qw INVENTORS WILL/AM E. YOU/V6 R510 A. MAHAFFY BY A51am. mm, m

ATTORNEYS Oct. 3, 1972 w YQUNG ETAL EVACUATED HERMETICALLY SEALEDPACKAGE WITH SEMIRIGID SHELL AND STRETCHABLE CLOSURE Original FiledSept. 1. 1965 2 Sheets-Sheet I nited States Patent ()lice 3,695,900Patented Oct. 3, 1972 EVACUATED HERMETICALLY SEALED PACKAGE WITHSEMIRIGID SHELL AND STRETCHABLE CLOSURE William E. Young, Stamford,Conn., and Reid A. Mahafiy, Montclair, N.J., assiguors to Reid A.Mahatiy, John R. Harder, and American Can Company, fractional partinterest to each Continuation of application Ser. No. 484,249, Sept. 1,1965. This application July 22, 1970, Ser. No. 64,034

Int. Cl. 1365b 25/06, 31/02 US. Cl. 99-174 19 Claims ABSTRACT OF THEDISCLOSURE Evacuated hermetically sealed package comprising a top ofstretchable plastic film sealed to a semi-rigid shell containing aproduct with the stretchable top in tight contact with the upper surfaceof the product. The package is formed by apparatus including a packaginghead having preliminary and final sealing means. The preliminary sealingmeans include heat seal bars extending part way around the periphery ofthe shell and a heating element mounted within the space interiorly ofthe seal bars which softens the top and renders it readily stretchablein the area inboard of the seal line. Final seal means including anevacuating chamber and means to complete the seal between the top andshell. The application of atmospheric pressure upon venting theevacuation chamber causes the top to stretch inwardly against theproduct.

This application is a continuation of Ser. No. 484,249 filed on Sept. 1,1965 and now abandoned.

This invention relates to packaging food products and the like inhermetically-sealed containers. More particularly, this inventionrelates to improved automatic packaging apparatus, packaging methods,and the packages made thereby.

Reference is made to copending application Ser. No. 64,035, filed by R.A. Mahatfy et al. on July 22, 1970, showing the basic subject matter ofthe present application (and including disclosure of additionalmaterial). To clarify the relationship between these two applications,it is noted that the present application is directed to the broadpackaging concepts wherein a semi-rigid evacuated package comprising acup-like receptacle or container is provided with a stretch-formed toparranged to reduce the transmittal of distorting stresses from the topto the container cup. Such package may be formed with a sequencedpressure application wherein pressure first is applied to the top andthereafter to the semi-rigid bottom. The top may be stretched subsequentto package evacuation, as by evacuation chamber, or the top may bepre-stretched prior to assembly and completion of the package, as byapplication of difierential pressure prior to the evacuation phase ofthe packaging operation. The copending application Ser. No. 64,035, onthe other hand, is directed to specific features including (a) atrapezoidal-like package configuration, (b) the use of a stifiprotective member as a third package element, (c) the technique whereinthe top is stretched by first moving it away from the semirigidcontainer (and the product contained therein) to a region adjacent aheater, and. thereafter forcing the top towards the container to stretchit, and (d) the use of a check valve to obtain the sequencedpressure-application technique more broadly claimed in the presentapplication.

For a number of years now, extensive use has been made of automaticapparatus for packaging products in evacuated containers formed offlexible plastic packaging material. In some cases, the products wereinserted in pre-formed pouches which were then evacuated and sealedalong the opening. Subsequently (see, for example, US. Patent3,061,984), completely automatic machines were developed to formpackages from two sheets of flexible plastic film drawn from respectivesupply rolls. In either case, the resulting container was formedentirely of thin flexible film. Thus the ultimate evacuation of thecontainer caused the film to be forced inwardly by atmospheric pressureinto close and intimate pressure-contact with the enclosed product, anddistorting the film into a shape conforming to the product profile.

For many products, such as luncheon meat and frankfurters, this approachprovided reasonably accetpable results. However, it was not reallysatisfactory for certain other types of products. For example, whenpackaging a shingled group of bacon slices it has been found that thepressure applied by the atmosphere through the film to all parts of thebacon tends to cause undesirable cohesion of the individual strips ofbacon after the container is opened by the purchaser. Also, theresulting container does not afford prospective customers the bestpresentation of the bacon through the stretched and distorted parts ofthe film.

Accordingly, it is one object of this invention to provide an evacuatedpackage which is superior to those available heretofore. Another objectof this invention is to provide improved vacuum packaging apparatus andmethods. Still another object of this invention is to provide noveltechniques for packaging certain specialty products such as bacon. Otherobjects, aspects and advantages of this invention will in part bepointed out in, and in part apparent from, the following descriptionconsidered together with the accompanying drawings, in which:

FIG. 1 is a longitudinal vertical section through a part of thepackaging machine;

FIG. 2 is a detail horizontal section (from below), showing thepreliminary sealing means of the packaging head;

FIG. 3 is a perspective view of a completed package;

FIG. 4 is a cross-section taken along line 4-4 of FIG. 3;

FIG. 5 is a detail view, greatly magnified, of one corner of FIG. 4.

Referring now to FIG. 1, the packaging apparatus comprises a series oftrays .10 each adapted to receive and snugly support a correspondingcup-like receptacle 12 carrying the product 14, in this case a one poundshingled group of bacon slices. These trays are power-driven from rightto left with an intermittent cyclical indexing move- 0 ment to permitcertain sequential packaging operations to be performed at respectivestations along the path of movement.

Receptacles 12 are made of transparent, calendered, non-plasticizedpolyvinyl chloride, advantageously having a thickness in the range offive to fifteen mils. Such polyvinyl chloride is semi-rigid, meaningthat is is self-supporting and substantially retains its shape undernormal conditions of use, e.g. with a normal product load such as mightbe simulated by filling the receptacle with water. The receptacles arein the shape of a truncated triangular prism, best illustrated in FIG.3, and having a cross-section in the form of an isosceles trapezoid asshown in FIG. 4. The receptacles are formed with flat peripheral flanges16 extending entirely around the opening, and lying in a common plane.

Above two adjacent positions of the trays is a packaging head generallyindicated at 18 and mounted (by conventional means, not shown) forvertical reciprocating movement in synchronism with the indexing of thetrays. That is, when the trays stop, head 18 moves down to carry outcertain operations to be described, and then rises just before the nextindexing movement, so as to permit the trays to be shifted horizontallywithout interference.

To the right of packaging head 18, a web of flexible plastic packagingfilm 20 descends vertically to a lay down roll 21. This roll aids inapplying the film to the top of the trays 10 as they are shifted intothe first position under the packaging head 18. The film is drawn from asupply roll (not shown) and has a width suflicient to cover thereceptacles 12 including the side flanges thereof. In the disclosedembodiment, film 20 is a laminate of Sarancoated polyester and polyvinylchloride, and the polyvinyl chloride side faces down to engage thepolyvinyl chloride receptacles '12. Thus the heat-sealing properties ofthe film 20 are compatible with those of the receptacles and bothprovide a good oxygen barrier.

The packaging head 18 includes both a preliminary seal means, generallyindicated at 22, and an evacuation and final seal means, generallyindicated at 2-4. The preliminary seal means further comprisesperipheral heat-sealing bars 26 (see FIG. 2) arranged to extend aroundthree flanges of the receptacle r12 and partially along the fourthflange. The gap in the heat-sealing bar along the fourth flange isfilled with a low thermal conductivity, heat-resistant elastomer 28,e.g. silicone rubber, the lower edge of which is in the same plane asthe heat sealing bars, or projects slightly below. Thus, when the head18 descends, it presses the film 20 tightly against all of the flanges16, sealing the film against air leakage around the entire periphery ofthe preliminary sealing means.

Also carried by the packaging head 18, within the preliminary seal means22, is a flat platen 30 the lower surface of which is about /s" abovethe plane of the heatsealing bars 26. The side edges of this platen arespaced a small distance from the interior side walls of the heatsealingbars. This platen is formed to receive a set of heater elements 32,additional to the sealing heaters 33,

to maintain the platen at a moderately elevated temperature.

When the packaging head 18 is in its lower position, the chamber definedby the preliminary sealing means 22 is evacuated by a vacuum line 36. Asshown in FIG. 1, this causes the film 20 to be forced uniformly upagainst the platen 30 so that the film becomes somewhat softened by theheat. Such softening makes it readily possible, by application ofreasonable pressure, to stretch the film, e.g. beyond its elastic limit,for purposes as will be described subsequently.

While the receptacle 12 is in the preliminary seal position, the heatedbars 26 operate in known manner to heat-seal the film 20 to thecorresponding receptacle 12 along three of the flanges 16. Since theelastomer 28 is not heated, that end of the receptacle is not sealed tothe film.

The head 18 thereafter rises and the partially sealed receptacle 12 isindexed to the next position where the evacuation and final sealing ofthe package take place. To this end, each tray 10 is provided with acaptive weblifter 38 which, in accordance with prior art techniques,

is shifted up (through a previously formed cut-out 12a in the receptacle12) to raise the end of the film 20 opposite the unsealed flange of thereceptacle. The package then is evacuated through the channel thuscreated between the film and the receptacle. The vacuum is drawn throughthe web-lifter passage in the tray, through a vertically reciprocablegasketed coupler 40, a line 42 including a check valve 44 and the mainvacuum valve 46 to which is connected a vacuum conduit 48. This mainvalve 46 also connects vacuum through a line 50 to the chamber above thefilm 20.

After evacuation, main valve 46 is shut off and an inert gas is admittedinto the package from a gas line 52. The gas passes through an internalconduit in the web-lifter support, and exits into the package through anaperture in the top of the web-lifter. When the proper amount of gas hasbeen admitted, the web-lifter is allowed to drop back down to its normalrest position and they usual heated final seal bar descends from abovethe film 20 to complete the heat-sealing of the film to the receptacle12. This final seal extends along the side of the receptacle interiorlyof the aperture 12a, and overlaps the preliminary seal lines so as tomake the package completely gas-proof.

Thereafter, main valve 46 is shifted to its vent positon, admittingatmospheric air through line 50 into the final seal chamber above thefilm 20. The check valve 44 momentarily restrains the flow of air intothe trays 10, but the air pressure above and below the package equalizesfairly quickly because some air will flow downward into the web-lifterpassage which is imperfectly closed off by the final seal bar in itslowered position. In some cases, it may be desirable to speed up thispressure equalization by providing an adjustable-restriction by-passvalve around the check valve 44.

Although the foregoing description applies particularly to packagingmachines of the type where evacuation is effected at one end of thepackage, this invention also is applicable to machines of the centerevacuation type as illustrated in US. Pat. 3,061,984. For such centerevacuation machines, two assemblies as illustrated in FIG. 2 are used ina side-by-side relationship with the elastomers 28 adjacent each other.The operation is identical, except that during venting to amtopshere noair will pass from the final seal chamber to the Web-lifter passagesince there is no exposed edge of the film around which it can pass.Hence the air that is admitted to the final seal chamber is somewhatmore effective in forming the film downward into the trays 12. It alsomay particularly be desirable to bleed air slowly through a bypass valvearound check valve 44 so that the coupler 40 will not adhere to thetray.

The inrush of atmospheric pressure above the film 20 serves to forcethis film down into the receptacle 12, causing the film to be stretched.The extent of stretching depends upon how much gas had previously beenadmitted into the package. Preferably, the admission of gas is adjustedto that amount which results in the edges of the bacon being pressedlightly against the interior surface of the receptacle 12 when thepackage is in its normal upright position as shown in FIG. 3.

The stretching of the fihn 20 interiorly of the flanges 16 is aided bythe heat applied in the preceding preliminary seal operation. Thus thefilm is somewhat softened so that it can be stretched, advantageously toan amount resulting in a permanent set of the plastic material. In anyevent, the film is force-fitted and stretched by the atmosphericpressure around all of the contours of the exposed pieces of bacon. Thereceptacle 12, being made of semirigid material, is not so formed aboutthe bacon but instead contacts the edges of the bacon with the desiredpressure engagement sufficient to assure that the bacon is immobilizedwithin the package. This arrangement particularly is advantageousbecause shifting of the bacon can smear grease on the interior of thereceptacle and interfere with a prospective customers inspection of theprodnet.

The pressure of the product against the interior of the receptacle 12should be suttficient to press any large flat product surfaces, such asthat of the end slice 14a, into full contact with the interior of thereceptacle. However, the pressure desirably is low enough to avoidsquashing the bacon edges 14b fiat against that interior. This degree ofpressure provides a superior package appearance while preventingshifting of the product, disarray and grease smearing.

The film 20 can be vacuum-formed, i.e. stretched beyond its elasticlimit, while in the preliminary sealing stage, for example to such anextent that no further stretching is needed in the final seal stage.Such stretching may be useful in some applications, and is facilitatedby the effective air-tight seal around all four sides at the preliminaryseal means, as well as by the heat transferred to the film by the platen30. When forming the film in the preliminary sealing position, theplaten 30 advantageously is placed more than Vs" above the plane of theheat sealing bars 26, e.g. at a distance approximately equal to theextent of forming desired. For some applications, the need forpre-heating and/or pre-stretching the film may be reduced or evenavoided, as by the use of film material having suitable characteristicsof stretchability at normal ambient operating temperatures.

In the final seal stage, physical stretching of the interior marginalportions of the film 20 inwardly to the product 14, especially to apermanent set dimension, is desirable because it tends to eliminate anysubstantial buildup of tension in the film. As shown in FIG. 5, the filmis formed inwardly at 20a to follow the side wall contour of thereceptacle 12. Thus the force of the atmospheric pressure is carriedessentially by the packaged product, aided by the internal gas pressure.This avoids placing portions of the package under heavy stress, andminimizes distortion of the semi-rigid receptacle from its originalshape.

Although a preefrred embodiment of the invention has been set forth indetail, it is desired to emphasize that this is not intended to beexhaustive or necessarily limitative; on the contrary, the showingherein for the purpose of illustrating the invention and thus to enableothers skilled in the art to adapt the invention in such ways as meetthe requirements of particular applications, it being understood thatvarious modifications may be made without departing from the scope ofthe invention as limited by the prior art.

We claim:

1. A composite evacuated package comprising a relatively thicksemi-rigid cup-like shell member of gasimpermeable material, said shellmember having a base portion and side wall portions defining boundariesof an opening into said shell member, said shell member furtherincluding flanges around said opening; a product in said package, saidproduct being no more than slightly smaller in lateral dimensions thansaid opening so as to provide a relatively close fit; a closure memberof stretchable and gas-impermeable plastic sheet extending across saidopening and heat-sealed to said shell member flanges, said closuremember having a central face region which is at least approximatelyplanar and generally parallel to said opening, said central face regionbeing forced against the adjacent surfaces of the packaged product byatmospheric pressure so as to press said product against said shell baseportion, said closure member further being formed adjacent said flangeswith stretched portions extending down into said shell between said sidewall portions and the closely adjacent side edges of the packagedproduct to the extent permitted by lateral space between said productand said shell, any portions of said stretched elements within suchlateral space being forced by atmospheric pressure inwardly against theside edges of said product and outwardly against said side wall portionsof said shell member.

2. A composite evacuated and hermetically sealed package comprising arelatively thick semi-rigid cup-like shell member of gas-impermeablematerial, said shell member having a base portion and side wall portionsdefining boundaries of an opening into said shell member, said shellmember further including flanges around said opening; a product in saidpackage, said product having lateral dimensions providing a close fitwithin the side walls of said shell member; the upper surfaces of saidproduct being vertically displaced from said shell member flanges atleast at a portion of the product adjacent the side wall of said shellmember; a closure member of gasimpermeable plastic sheet extendingacross said opening and heat-sealed to said shell member flanges, saidclosure member having a central face region which is generally parallelto said opening, said central face region being forced against theadjacent surfaces of the packaged product by atmospheric pressure so asto hold said product tightly in position pressed against said shell baseportion, said closure member further being formed adjacent said flangeswith stretched elements extending away from said shell flanges to saidupper surfaces of said product portion adjacent said side wall region,said elements being stretched to an extent avoiding the development ofdistorting tensions applied to said semi-rigid shell member fromatmospheric pressure so that the atmospheric pressure load is carried bythe packaged product; said stretched elements being forced byatmospheric pressure tightly against said product portion adjacent saidside wall region and outwardly against any side wall portion of saidshell member lying between said product portion upper surface and theadjacent flange, whereby the volume of the evacuated semi-rigidcontainer adjusts to the size of the product so as to obtain themechanical protection of a semi-rigid shell member while substantiallyeliminating voids within the evacuated interior.

3. A package as claimed in claim 2, wherein said elements are stretchedbeyond the elastic limit of said plastic sheet material.

4. The method of forming an hermetically-sealed package comprising thesteps of securing a stretchable plastic sheet top over the opening of asemi-rigid cup containing a product to be packaged; evacuating theinterior of the resulting package while providing a reduced pressure inthe spaces above the package top and beneath the package cup;hermetically sealing the package; venting the space above the packagetop to provide a forceful pressing of the top down against the packagedproduct; and thereafter venting the space beneath the package cup.

5. The method of forming an hermetically-sealed package comprising thesteps of placing in a semi-rigid cup having horizontal flanges aroundthe opening a product the upper surfaces of which are below said flangesat least in the regions adjacent the side walls of the cup; sealing aplastic sheet top to said flanges at least substantially around saidopening; evacuating the interior of the package while providing areduced pressure in the spaces above the package top and beneath thepackage cup; hermetically sealing the package, venting the space abovethe package top to provide a forceful pressing of the plastic sheet topdown against the packaged product; and thereafter venting the spacebeneath the package cup.

6. The method of making an evacuated and hermetically sealed package bymeans of an automatic packaging machine carrying out the process stepsof:

supporting a semi-rigid tray-like shell member of relatively thick,gas-impermeable packaging material having a bottom portion withupstanding wall portions defining boundaries of an opening into saidshell member and being provided with flanges around said opening, saidshell member containing a product having lateral dimensionssubstantially the same as said opening so as to provide a close fitwithin said upstanding wall portions, the upper surfaces of said productbeing vertically displaced from said flanges, at least at the portionsof said product adjacent the side wall of said shell member;

advancing said shell member through a series of positions;

advancing through a series of positions a sheet of heatstretchable andgas-impermeable plastic packaging material which at one stage of thepackage-making process is disposed over the opening of the shell memberand is sealed thereto around a peripheral region;

heating said plastic sheet in one of said positions thereof to softenthe marginal portions of said sheet inboard of said peripheral regionsufliciently to permit stretching of said marginal portions;

stretching said heated marginal portions of said plastic sheet to createa central face portion and stretched side portions adapted to extendaway from said shell member flanges at least to the level of the uppersurfaces of said product portions which lie next to said shell memberwall portions;

evacuating said shell member while said platic sheet is disposedthereover;

applying heat to said packaging material while said shell member isevacuated with said sheet disposed thereover, said heat being applied soas to effect a permanent heat-seal to form said shell member and saidsheet into a gas-tight package the internal pressure of which is lessthan atmospheric; and exposing the exterior of the package toatmospheric pressure with said package sufliciently evacuated that theexternal atmospheric pressure forces said central face portion tightlyagainst the upper surfaces of the packaged product and presses saidstretched side portions tightly against all immediately adjacentsurfaces of said shell and said product, the stretching of said sideportions being sufi'icient to prevent the atmospheric pressure fromdeveloping tensional stresses therein tending to distort the shellmember.

7. The method of making an evacuated and hermetically sealed package byan automatic packaging machine carrying out the process steps of:

supporting a semi-rigid tray-like shell member of relatively thick,gas-impermeable packaging material having a bottom portion withupstanding wall portions defining boundaries of an opening into saidshell member and being provided with flanges around said opening, saidshell member containing a product having lateral dimensionssubstantially equal to said opening so as to provide a close fit withinsaid upstanding wall portions; the upper surfaces of said product beingbelow said flanges adjacent the side wall of said shell member;

advancing said shell member through a series of positions;

advancing through a series of positions a sheet of heat-stretchable andgas-impermeable plastic packaging material which at one stage of thepackagemaking process is disposed over the opening of the shell memberand is sealed thereto around a peripheral region;

heating said plastic sheet at one of said positions thereof to softenthe marginal portions of said sheet inboard of said peripheral regionsuificiently to permit substantial stretching of said marginal portions;

reducing the pressure in said chamber;

evacuating the interior of said shell member while in i said chamber;

applying heat to said packaging material while in said chamber to effecta permanent heat-seal to form a gas-tight hermetically-sealed packagethe internal pressure of which is substantially less than atmospheric;and '1 venting said chamber to apply substantially increased pressure tothe outside surfaces of the hermetically sealed and evacuated packagestructure suflicient to stretch said heated marginal portions of saidplastic sheet down towards the packaged product, the applied pressureforcing the central portion of the plastic sheet interiorly of saidstretched portions against the upper surfaces of the packaged product,the applied pressure further forcing the stretched marginal portionsoutwardly against the adjacent wall portions of the semi-rigid shellmember to eifectively eliminate voids in the package, the stretching ofsaid marginal portions being sufficient to prevent the atmosphericpressure force on said plastic sheet from developing tensional stressestherein tending to distort the shell member.

8. Apparatus for making packages comprising, in combination, a series ofreceiving elements adapted to be mounted in an endless loop arranged formovement past a series of packaging stations where sequential packagingoperations are performed, said elements including means to supportrespective cup-like members of semi-rigid material adapted to receiveproducts to be packaged; means to apply to said elements a film offlexible packaging material over the opening of each cup-like member insequence; a packaging head at one of said stations and including meansoperable to seal said film to the respective cup-like member in a regionextending around the periphery thereof; heating means within saidpackaging head to raise the temperature of said film interiorly of saidsealed region; and evacuating means to withdraw air from the package tothe extent that atmospheric pressure forces said heated flexible filminwardly against the product by stretching said film interiorly of saidsealed region.

9. Apparatus for making packages comprising, in combination, a series ofreceiving elements adapted to be mounted in an endless loop arranged formovement past a series of packaging stations where sequential packagingoperations are performed, said elements including means to supportrespective cup-like members of semi-rigid material adapted to receiveproducts to be packaged; means to apply to said elements a film offlexible packaging material over the opening of each cup-like member insequence; a packaging head at one of said stations and including meansoperable to seal said film to the respective cup-like member in a regionextending around the periphery thereof; support means to engage thebottom surfaces of the cup-like member at said one station; first vacuummeans at said one station to withdraw air from the package and to reducethe pressure on the outside surface of said semi-rigid member duringevacuation of the package; second vacuum means at said one station toreduce the pressure on the outside surface of said film during saidevacuation; and control means for venting said second vacuum means toatmosphere, said control means including means automatically operableupon vent-' ing of said second means to retain reduced pressure on theoutside surface of said semi-rigid member for a short period of time andthereafter to cause that pressure to equal the atmospheric pressure onsaid film, the atmospheric pressure during said short period of timeforcing said flexible film downwardly against the product to stretchsaid film interiorly of said sealed region, the bottom surfaces of thecup-like member being supported by said support means against thedownward pressure of atmosphere during said short period of time.

10. Apparatus for making packages comprising, in combination, a seriesof receiving elements adapted to be mounted in an endless loop arrangedfor movement past a series of packaging stations where sequentialpackaging operations are performed, said elements including means tosupport respective cup-like members of semi-rigid material'adapted toreceive products to be packaged; means to apply -to said elements a filmof flexible packaging material over the openingof each cup-like memberin sequence; a packaging head at one of said stations and includingpreliminary sealing means and final sealing means, said preliminarysealing means including heated seal bars extending part way around theperiphery of each member to seal said film to the respective cup-likemember while leaving an opening at one region for subsequent evacuationof the package; a heating element mounted in said packaging head withinthe space interiorly of said seal bars and arranged to raise thetemperature of said film interiorly of said sealed region; and

evacuating means at said final sealing means to withdraw air from thepackage such that atmospheric pressure forces said heated flexible filminwardly against the product by stretching said film interiorly of saidsealed reglop.

11. Apparatus as claimed in claim 10, wherein said heating elementcomprises a platen disposed parallel to the surface of the film.

12. Apparatus as claimed in claim 11, including an unheated memberbridging the gap between the ends of said seal bars at said region, andvacuum means for evacuating the spaces around said heating element todraw said film into contact therewith.

13. Apparatus for making packages comprising, in combination, a seriesof receiving elements adapted to be mounted in an endless loop arrangedfor movement past a series of packaging stations where sequentialpackaging operations are performed, said elements including means tosuport respective cup-like members of semi-rigid material adapted tocontain products to be packaged; means to apply to said elements a sheetof stretchable plastic packaging material with the sheet beingpositioned over the opening of each cupJike member in sequence to form apackage structure; a packaging head at one of said stations andincluding means operable to seal said sheet to the respective cup-likemember in a region extending around the periphery thereof; heating meanswithin said packaging heard arranged to raise the temperature of saidplastic sheet interiorly of said peripheral sealed region, said heatingmeans comprising a heated element positioned closely adjacent saidplastic sheet to transfer heat thereto interiorly of said sealed region;and evacuating means to withdraw air from the package to such an extentthat atmospheric pressure forces said heated plastic sheet inwartilyagainst the product by stretching said sheet interiorly of said sealedregion.

14. Apparatus for making evacuated packages of semin'gid type andcomprising, in combination, a series of receiving elements mounted in anendless loop for movemerit past a series of packaging stations wheresequential packaging operations are performed, said receiving elemeritsincluding means to support respective cup-like members of semi-rigidmaterial adapted to contain products to be packaged; means to apply tosaid elements a continuous sheet of stretchable plastic packagingmaterial with the sheet positioned over the periphery of the opening ofeach cup-like member in sequence to form a corresponding packagestructure; relatively reciprocable packaging head means adjacent thepath of movement of said receiving elements; said packaging head meanscomprising means to evacuate and hermetically seal said packagestructure, including means operable to seal said sheet to the respectivecup-like member throughout a region extending around the periphery ofthe opening thereof; said packaging head means also including heatingmeans to raise the temperature of said plastic sheet interiorly of saidperipheral sealing region and comprising a heated element positionedclosely adjacent the plastic sheet to transfer heat thereto; saidpackaging head means further including means to create a pressuredifferential across the heated areas of said plastic sheet to stretchthe marginal sheet portions inboard of said peripheral sealing region ina direction generally perpendicular to the surface of the plastic sheet,said stretched portions being held by atmospheric pressure in a positionextending into said cup-like member and pressed against the side wallsthereof after the evacuated and sealed package has been completed.

15. Apparatus for making evacuated packages of semirigid type andcomprising, in combination, a series of receiving elements mounted formovement past a series of packaging stations Where sequential packagingoperations are performed, said receiving elements including means tosupport respective cup-like members of semirigid material adapted tocontain products to be packaged; means to apply to said elements a.continuous sheet of stretchable plastic packaging material with thesheet positioned over the periphery of the opening of each cuplikemember in sequence to form a corresponding package structure; heatingmeans to raise the temperature of said plastic sheet comprising a heatedelement positioned closely adjacent the plastic sheet to transfer heatthereto; means to create a pressure differential across the heated areasof said plastic sheet to stretch the marginal sheet portions thereof ina direction generally perpendicular to the surface of the plastic sheet,relatively reciprocable packaging head means adjacent the path ofmovement of said receiving elements; said packaging head meanscomprising means to evacuate and hermetically seal each packagestructure, said stretched portions being held by atmospheric pressure ina position extending into said cup-like member and pressed against theside walls thereof after the evacuated and sealed package has beencompleted.

16. Apparatus for making evacuated packages of semirigid type whereinthe upper surfaces of the product are displaced vertically with respectto the opening of the container, at least in the portions of the productadjacent the edges of the opening, said apparatus comprising, incombination, a plurality of receiving elements mounted for movement pasta series of packaging stations where sequential packaging operations areperformed, said receiving elements including means to support semi-rigidmaterial formed into cup-like container members adapted to containproducts to be packaged; means to advance towards said elements acontinuous sheet of plastic packaging material with the sheet positionedover the opening of each cup-like member in sequence to form therewith acorresponding package structure; package forming means adjacent the pathof movement of said receiving elements and comprising heating means andmeans to evacuate the package structures; said heating means includingmeans operable to hermetically seal each package structure includingmeans to seal said sheet to the respective cup-like member throughout aregion extending around the periphery of the cup opening; said heatingmeans further including means to transfer heat to the marginal portionsof said plastic sheet immediately inboard of said peripheral sealingregion to raise the temperature of said marginal portions to a levelsufficient for stretching thereof by application of pressure; said package forming means also including means to create a pressure differentialacross said plastic sheet to stretch said marginal sheet portions in adirection generally perpendicular to the surface of the plastic sheet todevelop stretched marginal portions which in the completed package areheld by atmospheric pressure pressed against all immediately adjacentsurfaces of the contained product and the cuplike member.

17. Apparatus as claimed in claim 16, wherein said means to evacuatesaid package structure comprises a relatively movable member at onepackaging station arranged when actuated to form an evacuation chamber;said receiving elements being arranged to transfer said packagestructures into position to 'be held within said chamber; said means forheating said marginal portions of said plastic sheet being located at apackaging station preceding said one packaging station.

1-1 12 18. Apparatus as claimed in claim 17, wherein said 3,226,236 12/1965 Weller 99 171 means for creating a pressure differential is at apackaging 3,298,158 1/ 1967 Schmidt -3 53-l 12 station preceding saidone packaging station. 3,347,011 10/ 1967 Lovas et a1. 3.- 53- -21 19.Apparatus as claimed in claim 17, wherein said 3,467,244 9/ 1969Mahalfy'et a1; L- 20645.34" means for creating a pressure differentialcomprises means 5 3,522,687 8/ 1970 Mahaffy 53 22 to vent said vacuumchamber after the package has been I 1 evacuated and hermetically sealedby said package MORRIS Pflmary Examlnel forming means. B D A IReferences Cited S. v V S, Assistant Examiner UNITED STATES PATENTS -SQJ. A .7 2,834,686 5/1958 Reuman 99-171 53--22 A, 30,39, 42,-112 A, 141,184; 99- 17,1-LM,

3,034,271 5/1962 Carpenter et al 53-184 TC, 171 LP; 206-46 F UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,695,900Dated October 3 1972 Invent fl William E. Younq. et. al

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 7, line 69, insert placing said shell member with said plasticsheet disposed thereover in a sealed chamber;

Signed and sealed this 20th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. I 7 ROBERT GOTTSCHALK Attesting OfficerCommissioner of Patents ORM PO-1050 (10-69) USCOMM-DC 6O376-P us.GOVERNMENT PRINTING OFFICE: 1959 03ss-3:u

